CentOS7安裝使用MySQL

安裝MySQL

添加mysql源

# rpm -Uvh http://repo.mysql.com//mysql57-community-release-el7-7.noarch.rpm

安裝mysql

# yum -y install mysql-community-server

啟動mysql並設置為開機自啟動服務

# chkconfig mysqld on
# service mysqld start

檢查mysql服務狀態

# service mysqld status

第一次啟動mysql，會在日志文件中生成root用戶的一個隨機密碼，使用下面命令查看該密碼

# grep 'temporary password' /var/log/mysqld.log

修改root用戶密碼

# mysql -u root -p -h localhost
Enter password:

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'Mysql-2016';

 創建數據庫（數據庫名為：crashcourse）

mysql> create database crashcourse;

使用crashcourse數據庫

mysql> use crashcourse;

執行sql腳本（使用source命令）

mysql> source /root/MySQLCrashCourse/create.sql; 
mysql> source /root/MySQLCrashCourse/populate.sql;

查看可用數據庫的列表

mysql> show databases;

 查看當前數據庫內可用表的列表

mysql> show tables;

顯示表列（表名：customers）

mysql> show columns from customers;

 顯示服務器錯誤或警告消息

mysql> show errors;
mysql> show warnings;

檢索數據

檢索單個列

mysql> select prod_name from products;

檢索多個列

mysql> select prod_id, prod_name, prod_price from products;

檢索所有列（除非你確實需要表中的每個列，否則最好別使用*通配符，因為會降低應用程序的性能）

mysql> select * from products;

檢索不同的行（使用distinct關鍵字）

mysql> select distinct vend_id from products;

限制結果

返回不多於5行
mysql> select prod_name from products limit 5;
檢索的開始行和行數
mysql> select prod_name from products limit 5,5;

使用完全限定的表名

mysql> select products.prod_name from crashcourse.products;

排序檢索數據

排序數據

mysql> select prod_name from products order by prod_name;

按多個列排序

mysql> select prod_id, prod_price, prod_name from products order by prod_price, prod_name;

指定排序方向（使用desc關鍵字，desc為倒序，默認是asc，正序）

mysql> select prod_id, prod_price, prod_name from products order by prod_price desc;

使用order by和limit的組合

mysql> select prod_price from products order by prod_price desc limit 1;

過濾數據

檢索單個值

mysql> select prod_name, prod_price from products where prod_name = 'fuses';

不匹配檢查

mysql> select vend_id, prod_name from products where vend_id != 1003;

范圍值檢查

mysql> select prod_name, prod_price from products where prod_price between 5 and 10;

空值檢查

mysql> select prod_name from products where prod_price is null;

數據過濾

and操作符

mysql> select prod_id, prod_price, prod_name from products where vend_id = 1003 and prod_price <= 10;

or操作符

mysql> select prod_name, prod_price from products where vend_id = 1003 or prod_id = 1003;

計算次序

mysql> select prod_name, prod_price from products where (vend_id = 1002 or vend_id = 1003) and prod_price >= 10;

in操作符

mysql> select prod_name, prod_price from products where vend_id in (1002,1003) order by prod_name;

not操作符

mysql> select prod_name, prod_price from products where vend_id not in (1002,1003) order by prod_name;

用通配符進行過濾

百分號（%）通配符（匹配0,1或多個字符）

mysql> select prod_id, prod_name from products where prod_name like 'jet%';

下划線（_）通配符（匹配1個字符）

mysql> select prod_id, prod_name from products where prod_name like '_ ton anvil';

用正則表達式進行搜索

基本字符匹配

mysql> select prod_name from products where prod_name regexp '.000' order by prod_name;

進行or匹配

mysql> select prod_name from products where prod_name regexp '1000|2000' order by prod_name;

匹配范圍

mysql> select prod_name from products where prod_name regexp '[1-5] Ton' order by prod_name;

匹配特殊字符（使用\\進行轉義）

mysql> select vend_name from vendors where vend_name regexp '\\.' order by vend_name;

匹配字符類

mysql> select prod_name from products where prod_name regexp '[[:digit:]]{4}' order by prod_name;

匹配多個實例

mysql> select prod_name from products where prod_name regexp '\\([0-9] sticks?\\)' order by prod_name;

定位符（^, $, [[:<:]], [[:>:]]）

mysql> select prod_name from products where prod_name regexp '^[0-9\\.]' order by prod_name;

創建計算字段

拼接字段

mysql> select concat(vend_name, ' (', vend_country, ')') from vendors order by vend_name;

使用別名

mysql> select concat(rtrim(vend_name), ' (', rtrim(vend_country), ')') as vend_title from vendors order by vend_name;

執行算術計算

mysql> select prod_id, quantity, item_price, quantity*item_price as expanded_price from orderitems where order_num = 20005;

使用數據處理函數

文本處理函數

mysql> select vend_name, upper(vend_name) as vend_name_upcase from vendors order by vend_name;
mysql> select cust_name, cust_contact from customers where soundex(cust_contact) = soundex('Y Lie');

日期和時間處理函數

mysql> select cust_id, order_num from orders where date(order_date) between '2005-09-01' and '2005-09-30';
mysql> select cust_id, order_num from orders where year(order_date) = 2005 and month(order_date) = 9;

匯總數據

avg()函數

mysql> select avg(prod_price) as avg_price from products;

count()函數

mysql> select count(*) as num_cust from customers;

max()函數

mysql> select max(prod_price) as max_price from products;

min()函數

mysql> select min(prod_price) as min_price from products;

sum()函數

mysql> select sum(quantity) as items_ordered from orderitems where order_num = 20005;
mysql> select sum(item_price*quantity) as total_price from orderitems where order_num = 20005;

聚合不同的值

mysql> select avg(distinct prod_price) as avg_price from products where vend_id = 1003;

組合聚集函數

mysql> select count(*) as num_items, min(prod_price) as price_min, max(prod_price) as price_max, avg(prod_price) as price_avg from products;

 分組數據

創建分組

mysql> select vend_id, count(*) as num_prods from products group by vend_id;

過濾分組（使用having關鍵字）

mysql> select cust_id, count(*) as orders from orders group by cust_id having count(*) >= 2;
mysql> select vend_id, count(*) as num_prods from products where prod_price >= 10 group by vend_id having count(*) >= 2;

分組和排序

mysql> select order_num, sum(quantity*item_price) as ordertotal 
    from orderitems 
    group by order_num 
    having sum(quantity*item_price) >= 50 
    order by ordertotal;

使用子查詢

利用子查詢進行過濾

mysql> select cust_name, cust_contact
    from customers
    where cust_id in (select cust_id
     from orders
     where order_num in (select order_num
     from orderitems
     where prod_id = 'TNT2'));

作為計算字段使用子查詢

mysql> select cust_name, cust_state,
                (select count(*)
                from orders
                where orders.cust_id = customers.cust_id) as orders
            from customers
            order by cust_name;

聯結表

創建聯結

mysql> select vend_name, prod_name, prod_price 
            from vendors, products
            where vendors.vend_id = products.vend_id
            order by vend_name, prod_name;

內部聯結

mysql> select vend_name, prod_name, prod_price
            from vendors inner join products
            on vendors.vend_id = products.vend_id;

聯結多個表

mysql> select cust_name, cust_contact
            from customers, orders, orderitems
            where customers.cust_id = orders.cust_id
            and orderitems.order_num = orders.order_num
            and prod_id = 'TNT2';

創建高級聯結

使用別名

mysql> select cust_name, cust_contact
            from customers as c, orders as o, orderitems as oi
            where c.cust_id = o.cust_id
            and oi.order_num = o.order_num
            and prod_id = 'TNT2';

自然聯結

mysql> select c.*, o.order_num, o.order_date, oi.prod_id, oi.quantity, oi.item_price
            from customer as c, orders as o, orderitems as oi
            where c.cust_id = o.cust_id
            and oi.order_num = o.order_num
            and prod_id = 'FB';

外部聯結

mysql> select customers.cust_id, orders.order_num
            from customers left join orders
            on customers.cust_id = orders.cust_id;

使用帶聚集函數的聯結

mysql> select customers.cust_name, customers.cust_id,
                count(orders.order_num) as num_ord
            from customers inner join orders
            on customers.cust_id = orders.cust_id
            group by customers.cust_id;

組合查詢

使用union

mysql> select vend_id, prod_id, prod_price
            from products
            where prod_price <= 5
            union
            select vend_id, prod_id, prod_price
            from products
            where vend_id in (1001,1002);

包含重復的行（使用union all命令）

mysql> select vend_id, prod_id, prod_price
            from products
            where prod_peice <= 5
            union all
            select vend_id, prod_id, prod_price
            from products
            where vend_id in (1001,1002);

對組合查詢結果排序

mysql> select vend_id, prod_id, prod_price
            from products
            where prod_price <=5
            union
            select vend_id, prod_id, prod_price
            from products
            where vend_id in (1001,1002)
            order by vend_id, prod_price;

全文搜索

僅在MyISAM數據庫引擎中支持全文搜索，一般在創建表時啟用全文搜索

CREATE TABLE productnotes
(
    note_id      int          NOT NULL  AUTO_INCREMENT,
    prod_id      char(10)       NOT NULL,
    note_date  datetime      NOT NULL, 
    note_text   text             NULL,
    PRIMARY KEY(note_id),
    FULLTEXT(note_text)
) ENGINE=MyISAM;

進行全文本搜索

mysql> select note_text
            from productnotes
            where match(note_text) against('rabbit');

使用查詢擴展

mysql> select note_text
            from productnotes
            where match(note_text) against('anvils' with query expansion);

布爾文本搜索

mysql> select note_text
            from productnotes
            where match(note_text) against('heavy' in boolean mode);

為匹配包含heavy但不包含任意以rope開始的詞的行

mysql> select note_text
            from productnotes
            where match(note_text) against('heavy -rope*' in boolean mode);

插入數據

插入完整的行

mysql> insert into customers(cust_name,
    cust_contact,
    cust_email,
    cust_address,
    cust_city,
    cust_state,
    cust_zip,
    cust_country)
values('Pep E. LaPew',
    Null,
    Null,
    '100 Main Street',
    'Los Angeles',
    'CA',
    '90046',
    'USA');

插入多個行

mysql> insert into customers(cust_name,
    cust_address,
    cust_city,
    cust_state,
    cust_zip,
    cust_country)
values(
    'Pep E. LaPew',
    '100 Main Street',
    'Logs Angeles',
    'CA',
    '90046',
    'USA'
),
(
    'M. Martian',
    '42 Galaxy Way',
    'New York',
    'NY',
    '11213',
    'USA'
);

插入檢索出的數據

mysql> insert into customers(cust_id,
    cust_contact,
    cust_email,
    cust_name,
    cust_address,
    cust_city,
    cust_state,
    cust_zip,
    cust_country)
select cust_id,
    cust_contact,
    cust_email,
    cust_name,
    cust_address,
    cust_city,
    cust_state,
    cust_zip,
    cust_country
from custnew;

更新和刪除數據

更新數據

mysql> update customers
    set cust_name = 'The Fudds',
        cust_email = '[e-mail]'
where cust_id = 10005;

刪除數據

mysql> delete from customers
    where cust_id = 10006;

創建和操縱表

創建表

mysql> create table customers(
    cust_id            int        NOT NULL AUTO_INCREMENT,
    cust_name     char(50)      NOT NULL,
    cust_address   char(50)     NULL,
    cust_city         char(50)     NULL,
    cust_state       char(5)       NULL,
    char_zip          char(10)     NULL,
    char_country   char(50)    NULL,
    char_contact    char(50)    NULL,
    char_email      char(255)   NULL,
    PRIMARY KEY (cust_id)
) ENGINE=InnoDB;

指定默認值

mysql> create table orderitems(
    order_num    int                NOT NULL,
    order_item    int                NOT NULL,
    prod_id         char(10)        NOT NULL,
    quantity        int                 NOT NULL   DEFAULT  1,
    item_price    decimal(8,2)   NOT NULL,
    PRIMARY KEY (order_num, order_item)
) ENGINE=InnoDB;

引擎類型

InnoDB是一個可靠的事務處理引擎。
MEMORY在功能上等同於MyISAM，但是數據存儲在內存中，速度很快。
MyISAM是性能極高的引擎，支持全文搜索，但不支持事務處理。

更新表

給表添加一列：

mysql> alter table vendors
    add vend_phone char(20);

刪除剛剛添加的列：

mysql> alter table vendors
    drop column vend_phone;

ALTER TABLE的一種常見用途是定義外鍵：

mysql> alter table orderitems
    add constraint fk_orderitems_orders
    foreign key (order_num) references orders (order_num);

mysql> alter table orderitems
    add constraint fk_orderitems_products
    foreign key (prod_id) references products (prod_id);

mysql> alter table orders
    add constraint fk_orders_customers
    foreign key (cust_id) references customers (cust_id);

mysql> alter table products
    add constraint fk_products_vendors
    foreign key (vend_id) references vendors (vend_id);

刪除表

mysql> drop table customers2;

重命名表

mysql> rename table customers2 to customers;

對多個表重命名

mysql> rename table backup_customers to customers,
        backup_vendors to vendors,
        backup_products to products;

使用視圖

利用視圖簡化復雜的聯結

mysql> create view productcustomers as
    select cust_name, cust_contact, prod_id
    from customers, orders, orderitems
    where customers.cust_id = orders.cust_id
        and orderitems.order_num = orders.order_num;

用視圖重新格式化檢索出的數據

mysql> create view vendorlocations as
　　select concat(rtrim(vend_name), ' (', rtrim(vend_country), ')')
        as vend_title
    from vendors
    order by vend_name;

用視圖過濾不想要的數據

mysql> create view customeremaillist as
    select cust_id, cust_name, cust_email
    from customers
    where cust_email is not null;

使用視圖與計算字段

mysql> create view orderitemsexpanded as
    select order_num,
            prod_id,
            quantity,
            item_price,
            quantity*item_price as expanded_price
    from orderitems;

使用存儲過程

執行存儲過程（所有mysql變量都必須以@開始）

mysql> call productpricing(@pricelow,
                           @pricehigh,
                           @priceaverage);

創建存儲過程

mysql> create procedure productpricing()
    begin
        select avg(prod_price) as priceaverage
        from products;
    end;

刪除存儲過程

mysql> drop procedure productpricing;

使用參數

mysql> create procedure productpricing(
    out pl decimal(8,2),
    out ph decimal(8,2),
    out pa decimal(8,2)
)
begin
    select min(prod_price)
    into pl
    from products;
    select max(prod_price)
    into ph
    from products;
    select avg(prod_price)
    into pa
    from products;
end;

建立智能存儲過程

-- Name: ordertotal
-- Parameters: onumber = order number
--                     taxable = 0 if not taxable, 1 if taxable
--                     ototal = order total variable

create procedure ordertotal(
    in onumber int,
    in taxable boolean,
    out ototal decimal(8,2)
) comment 'Obtain order total, optionally adding tax'
begin

    -- Declare variable for total
    declare total decimal(8,2);
    -- Declare tax percentage
    declare taxrate int default 6;

    -- Get the order total
    select sum(item_price*quantity)
    from orderitems
    where order_num = onumber
    into total;

    -- Is this taxable?
    if taxable then
        -- Yes, so add taxrate to the total
        select total+(total/100*taxrate) into total;
    end if;

    -- And finally, save to out variable
    select total into ototal;

end;

taxable=0測試結果

call ordertotal(20005, 0, @total);
select @total;

taxable=1測試結果

call ordertotal(20005, 1, @total);
select @total;

檢查存儲過程

mysql> show create procedure ordertotal;

限制過程狀態結果

mysql> show procedure status like 'ordertotal';

使用游標

創建游標

create procedure processorders()
begin
    declare ordernumbers cursor
    for
    select order_num from orders;
end;

打開和關閉游標

-- 打開游標
open ordernumbers;
-- 關閉游標
close ordernumbers;

使用游標

create procedure processorders()
begin

    -- declare local variables
    declare done boolean default 0;
    declare o int;
    declare t decimal(8,2);

    -- declare the cursor
    declare ordernumbers cursor
    for
    select order_num from orders;
    -- declare continue handler
    declare continue handler for sqlstate '02000' set done=1;

    -- create a table to store the results
    create table if not exists ordertotals
        (order_num int, total decimal(8,2));

    -- open the cursor
    open ordernumbers;

    -- loop through all rows
    repeat

        -- get order number
        fetch ordernumbers into o;

        -- get the total for this order
        call ordertotal(o, 1, t);

        -- insert order and total into ordertotals
        insert into ordertotals(order_num, total)
        values(o, t);

    -- end of loop
    until done end repeat;

    -- close the cursor
    close ordernumbers;

end;

使用觸發器

創建觸發器

create trigger newproduct after insert on products
for each row select 'Product added';

刪除觸發器

drop trigger newproduct;

使用觸發器

-- insert觸發器
create trigger neworder after insert on orders
for each row select new.order_num;

-- delete觸發器
create tigger deleteorder before delete on orders
for each row
begin
　　insert into archive_orders(order_num, order_date, cust_id)
　　value(old.order_num, old.order_date, old.cust_id);
end;

-- update觸發器
create trigger updatevendor before update on vendors
for each row set new.vend_state = upper(new.vend_state);

管理實務處理

事務（transaction）指一組SQL語句；

回退（rollback）指撤銷指定的SQL語句的過程；

提交（commit）指將未存儲的SQL語句結果寫入數據庫表；

保留點（savepoint）指事務處理中設置的臨時占位符，你可以對它發布回退。

使用rollback

select * from ordertotals;
start transaction;
delete from ordertotals;
select * from ordertotals;
rollback;
select * from ordertotals;

使用commit

start transaction;
delete from orderitems where order_num = 20010;
delete from orders where order_item = 20010;
commit;

使用保留點

savepoint delete1;

rollback to delete1;

更改默認的提交行為（設置autocommit為0，mysql不自動提交更改，直到autocommit為設置為1為止）

set autocommit=0;

全球化和本地化

字符集為字母和符號的集合；

編碼為某個字符集成員的內部表示；

校對為規定字符如何比較的指令。

查看所支持的字符集完整列表

show character set;

查看所支持校對的完整列表

show collation;

顯示數據庫所用的字符集和校對

show variables like 'character%';
show variables like 'collation%';

給表指定字符集和校對

create table mytable
(
　　column1　　int,
　　column2　　varchar(10)
) default character set hebrew
  collate hebrew_general_ci;

對每個列設置字符集和校對

create table mytable
(
　　column1　　int,
　　column2　　varchar(10),
　　columm3　  varchar(10) character set latin1 collate latin1_general_ci
) default character set hebrew
  collate hebrew_general_ci;

校對順序排序

select * from customers
order by lastname, firstname collate latin1_general_cs;

安全管理

不應該在日常的MySQL操作中使用root

獲得所有賬號列表

mysql> use mysql;
mysql> select user from user;

創建用戶賬號

mysql> create user ben identified by 'p@$$w0rd';

重命名用戶賬號

mysql> rename user ben to bforta;

刪除用戶賬號

mysql> drop user bforta;

查看用戶賬號權限

mysql> show grants for bforta;

給用戶賬號授予權限

mysql> grant select on crashcourse.* to bforta;

撤銷用戶權限

mysql> revoke select on crashcourse.* from bforta;

更改用戶口令

set password for bforta = password('n3w p@$$w0rd');

設置自己的口令

set password = password('n3w p@$$w0rd');

數據庫維護

備份數據

• 使用命令行實用程序mysqldump轉儲所有數據庫內容到某個外部文件
• 使用命令行實用程序mysqlhotcoy從一個數據庫復制所有數據
• 使用backup table或select into outfile轉儲所有數據到某個外部文件

數據庫維護

• analyze table用來檢查表鍵是否正確

mysql> analyze table orders;

• check table用來針對許多問題對表進行檢查

mysql> check table orders, orderitems;

• 如果從一個表中刪除大量數據，應該使用optimize table來回收所用的空間，從而優化表的性能

查看日志文件

• 錯誤日志。它包含啟動和關閉問題以及任意關鍵錯誤的細節。通常名為hostname.err
• 查詢日志。它記錄所有mysql活動，在診斷問題時非常有用。通常名為hostname.log
• 二進制日志。它記錄更新過數據的所有語句。通常名為hostname.bin
• 緩慢查詢日志。它記錄執行緩慢的任何查詢。通常名為hostname-slow.log

改善性能

查看當前設置

mysql> show variables;
mysql> show status;

顯示所有活動進程

mysql> show processlist;

• 如果某個任務執行緩慢，則所有的請求都會執行緩慢，可以用kill命令終結該進程。
• 總是有不止一種方法編寫同一條select語句，應該試驗聯結、並、子查詢等，找出最佳的方法。
• 使用explain語句讓mysql解釋它如何執行一條select語句。
• 一般來說，存儲過程執行比一條條地執行其中的各條mysql語句快。
• 應該總是使用正確的數據類型。
• 決不要檢索比需求還要多的數據。換言之，不要用select *（除非你真的需要每個列）。
• 有的操作（包括insert）支持一個可選的delayed關鍵字，如果使用它，將把控制立即返回給調用程序，並且一旦有可能就實際執行該操作。
• 在導入數據時，應該關閉自動提交。你可能還想刪除索引（包括fulltext索引），然后在導入完成后再重建它們。
• 必須索引數據庫以改善數據檢索的性能。確定索引什么不是一件微不足道的任務，需要分析使用的select語句以找出重復的where和order by子句。如果一個簡單的where子句返回結果所花的時間太長，則可以斷定其中使用的列（或幾個列）就是需要索引的對象。
• 你的select語句中有一系列復雜的or條件嗎？通過使用多條select語句和連接它們的union語句，你能看到極大的性能改進。
• 索引改善數據檢索的性能，但損害數據插入、刪除和更新的性能。如果你有一些表，它們收集數據且不經常被搜索，則在有必要之前不要索引它們。（索引可根據需要添加和刪除。）
• like很慢。一般來說，最好是使用fulltext而不是like。
• 數據庫是不斷變化的實體。一組優化良好的表一會兒后可能就面目全非了。由於表的使用和內容的更改，理想的優化和配置也會改變。
• 最重要的規則就是，每條規則在某些條件下都會被打破。